Method of and apparatus for increasing the volume of mechanicallyreproduced sounds



P 9, 1930. H. KUCHENMEISTER 1,775,248

METHOD OF AND APPARATUS FOR INCREASING THE VOLUME 0F MECHANICALLY REPRODUCED SOUNDS Filed Jan. 23, 1925 Patented Sept. 9, 1930 PATENT OFFICE HEINRICH Klj'CHENMEISTER, OF BERLIN, GERMANY METHOD AND APPARATUS FOR I NCREASING THE VOLUME OF MECHANIGALLY- REIPIRODUCED SOUNDS Application filed January 23, 1925, Serial No. 4,180, and in Germany February 2, 1924.

My invention has reference to sound-reproducing machines and more particularly to phonographs, gramophones, and the like. The object of my invention is to increase the volume of the sound produced by the reproducing means, and my invention consists in a novel method of accomplishing this object.

I have found that if two or more sound reproducing means are employed and during the reproduction a certain time interval is maintained between the reproduction of the sound by the first sound reproducing means and the reproduction of the sound by the other sound reproducing means, the quality of the sound thus reproduced is considerably;

improved and the sound thereby more nearly approaches the natural sound'either of the human voice, music instrument or the like, being reproduced. I have found that with a time interval of from about one sixth (1/6) to one fortieth (1/40) of a second between the first sound reproducing means and the other sound reproducing means a prolonga tion of the sound reproduced is obtained 2? which imparts to the. sound the character or quality of the natural sound, i. e. the sound which is being reproduced. The best results are obtained with a time interval of from one tenth (1/10) to one twentieth (1/20) of a second when used on phonographs and similar recording instruments in which disks are employed c'arriedby a rotatable support.

For a better illustration of my invention, I

refer to the accompanying drawing, show free end of the tone-arm 3 carrying the sound box 7 and stylus 11 forms with the tone-arm an acute angle, whereas, the elbow 10 of the 5g shorter tone-arm 4 carrying-the sound-box p 8 and stylus-12 is substantially at a right angle to its tone-arm.

In the starting position of the two tonearms, the actual distance between stylus 11 and stylus 12 is about 9 centimeters, while at the finish, 1. e; the position indicated by the broken lines, the distance between the two styluses is 4.5 centimeters. Because of this arrangement, a time interval of about one fifteenth 1/15) of a second is maintained between the sounds produced bythetwosound boxes or styluses as they move across the record, which time interval gives excellent results. At a uniform rotation of the rotata-v ble support 1, the two styluses travel, during a given time, almost twice as far along the outermost groove in the record than along the innermost groove. Therefore the distance between the two styluses 11 and 12 is gradually reduced from 9 centimeters at the starting point to 4.5 centimeters at the finish. Because there would otherwise be a more prolonged reproduction of the sound at the finish than at the start, which would disturb the uniformity in the sound reproduction.

To insure a uniform rotary movement of the sound record I prefer to provide the driving means at the circumference of the disk 1, said driving means being in the form of a roller 13 of rubber or the like frictionally engaging the edge of the disk and forming a part of a suitable driving mechanism not shown. I have found that where two tonearms 3 and 4 are used engaging the sound record, a central driving means such as ordinarily provided is not sufficient to overcome the increased resistance of the disk. Moreover the roller 13 engaging the edge of the disk 2 steadies the movement or" the disk by preventing oscillations in vertical direction caused by the weight of the tone arms 3 and i bearing'on the record disk on one side thereof. 7

The underlying principle'of my invention consists in a double or multiple reproduction of the sound by the same recording means with a suitable time interval between the sounds as reproduced by the first sound reproducing means and the sounds reproduced by the other sound reproducing means till) struction of its parts withoutfa departure While in describing the inventionI have made reference to a' particular embodiment of the same, I' wish it to be understood that my invention is of course not limited to the construction shown in the drawing, since various changes may be made in the general arrangement of the apparatus and'the confrom the essence of invention.

'I'claim: g e v 1.- In a "sound reproducing machine, means for supportingand rotating a grooved sound record, a pair of sound reproducing devices for cooperation with one another to repro--.

duce the same sound in the same location at time intervals indistinguishable to thevnormal ear, each of said devices being inclusive of 'a stylus, and means mounting, said dcvices so that said styli are disposed in spaced relation to one. another and adapted to track tandem in the groove-of said record, the distance between" said styliapproximating the angular distance traveled by any point in said record during rotation thereof at a normal rate of speed and during a time interval of from one-fortieth to one-sixth part of a second. r

2. In a sound reproducing machine, means for supporting and rotating a sound record of the disk type having a spiral record groove,.a pair of sound reproducing devices for cooperating with one another to reproduce the'same sound inthe samelocation at time intervals indistinguishable by the normal ear, each of. said devices being inclusive of a stylus, and means mounting said devices so that said styli are disposed in spaced relation to one another and adapted' to track tandem in thegroove of said record and in converging arcs towards the center of the record, the distance between said styli at all times approximating the angular distance traveled by any point in said record during rotation thereof at a normal rate of speed and during a time interval of from onefortieth to one-sixth part of a second.

i In testimony whereof I afiix my signature.

HEINRICH KU CHEN MEISTER. 

